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A076192
n == 1 mod 10 with property that n through n+9 contain no primes.
1
201, 321, 511, 531, 621, 841, 891, 1071, 1131, 1141, 1261, 1331, 1341, 1351, 1411, 1461, 1501, 1641, 1671, 1681, 1711, 1761, 1791, 1851, 1891, 1921, 1961, 2041, 2071, 2101, 2181, 2191, 2321, 2361, 2401, 2481, 2491, 2511, 2561, 2581, 2821, 2941, 2981
OFFSET
1,1
COMMENTS
Since a decade of consecutive numbers may contain up to 4 primes, more precisely a prime quadruple(p, p+2, p+6, p+8) within a decade k through k+9, where k=p-1 or p (=A007530) excepting the first case (2, 3, 5, 7), this sequence may be regarded as a counterpart to A007530.
Equals A078492(n-1) + 1 - Lekraj Beedassy, Jul 23 2003
EXAMPLE
531 is in the sequence because it is the first term of the ten consecutive composites:531 = 3^2*59; 532 = 2^2*7*19; 533 = 13*41; 534 = 2*3*89; 535 = 5*107; 536 = 2^3*67; 537 = 3*179; 538 = 2*269; 539 = 7^2*11; 540 = 2^2*3^3*5.
PROG
(PARI) isok(n) = {if ((n % 10) != 1, return (0)); for (k = 0, 9, if (isprime(n + k), return (0)); ); return (1); } \\ Michel Marcus, Jul 27 2013
CROSSREFS
Sequence in context: A347887 A353081 A259768 * A157956 A202771 A183350
KEYWORD
nonn
AUTHOR
Lekraj Beedassy, Oct 31 2002
EXTENSIONS
Edited, corrected and extended by Robert G. Wilson v, Nov 04 2002
STATUS
approved